The soul according to many religious and philosophical traditions, is the ethereal substance — spirit (Hebrew:rooah or nefesh) — particular to a unique living being. Such traditions often consider the soul both immortal and innately aware of its immortal nature, as well as the true basis for sentience in each living being.

The concept of the soul has strong links with notions of an afterlife, but opinions may vary wildly even within a given religion as to what happens to the soul after death. Many within these religions and philosophies see the soul as immaterial, while others consider it possibly material.

Note: This article uses the word "soul" in the common form, and deals largely with varied concepts from which the concept originates, and to which it relates. The use of the word soul often does not explicitly correspond to usage associated with any particular view or belief, including usage in Western and Eastern religious texts and in the writings of Plato, Aristotle, Heraclitus, or Plotinus.

Etymologies:

The current English word "soul" may have originated from Old English sawol, documented in 970 AD, which has possible etymological links with a Germanic root from which we also get the word "sea". The old German word is called 'se(u)la', what means: belonging to the sea (ancient Germanic conceptions involved the souls of the unborn and of the dead "living" be part of a medium similar to water).

Ancient Greeks sometimes referred to the soul as psyche (as in modern English psychology). Aristotle's works in Latin translation used the word anima (as in animated), which also means "breath". In the New Testament, the original word may sometimes better translate as "life", as in :

"For what profit is it to a man if he gains the whole world, and loses his own soul?" (Matthew 16:26)
If you exchange the word "soul" for "life" in the sentence above, the statement may seem less profound.

The Latin root of the related word spirit, like anima, also expresses the idea of "breath".

The various origins and usages demonstrate not only that what people call "soul" today has varied in meaning during history, but that the word and concept themselves have changed in their implications.

Philosophical views:

The Ancient Greeks used the same word for 'alive' as for 'ensouled'. So the earliest surviving Western philosophical view might suggest that the soul makes living things alive.

Socrates and Plato:

Plato, drawing on the words of his teacher Socrates, considers the soul as the essence of a person, as that which decides how we act. He considered this essence as an incorporeal occupant of our being. The Platonic soul comprises three parts:

1. the reason (mind or logos)
2. the appetite (body or passion)
3. spirit (emotion or pathos).

Each of these has a function in a balanced and peaceful soul.

The reason equates to the mind. It corresponds to the charioteer directing the balanced horses of appetite and spirit. It allows for logic to prevail and for the optimisation of balance.

The appetite drives humankind to seek out its basic bodily needs. Yet when the passion controls us, master passion drives us to hedonism in all forms. This is the basal and most feral state.

The spirit comprises our emotional motive, that which drives us to acts of bravery and glory. If left unchecked it will lead to hubris -- the most fatal of all flaws in the Greek view.

Aristotle:

Aristotle, following Plato, defined the soul as the core essence of a being, but argued against it having a separate existence. For instance, if a knife had a soul, the act of cutting would be that soul, because 'cutting' is the essence of what it is to be a knife. Unlike Plato and the religious traditions, Aristotle did not consider the soul as some kind of separate, ghostly occupant of the body (just as we cannot separate the activity of cutting from the knife). As the soul, in Aristotle's view, is an activity of the body it cannot be immortal (when a knife is destroyed, the cutting stops). More precisely, the soul is the "first activity" of a living body. This is a state, or a potential for actual, or 'second', activity. "The axe has an edge for cutting" was, for Aristotle, analogous to "humans have bodies for rational activity," and the potential for rational activity thus constituted the essence of a human soul. Aristotle used his concept of the soul in many of his works; the Nicomachean Ethics provides a good place to start to gain more understanding of his views.

Aristotle's view appears to have some similarity to the Buddhist 'no soul' view (see below). For both there is certainly no 'separable immortal essence'. It may simply become a matter of definition, as most Buddhists would agree, surely, that one can use a knife for cutting. They might, perhaps, stress the impermanence of the knife's cutting ability, and Aristotle would probably agree with that.

Religious views: - Buddhist beliefs

According to Buddhist teaching, all things are impermanent, in a constant state of flux, all is transient, and no abiding state exists. This applies to humanity as much as to anything else in the cosmos; thus, there is no unchanging and abiding self. Our sense of "I" or "me" is simply a sense belonging to the ever-changing entity that (conventionally speaking) is us, our body, and mind. This expresses in essence the Buddhist principle of anatta (Pali; Sanskrit: anatman).

Buddhists hold that the delusion of a permanent, abiding self is one of the main root causes for human conflict on the emotional, social and political levels. They add that understanding of anatta (or "not-self") provides an accurate description of the human condition, and that this understanding allows "us" to go beyond "our" mundane desires. Nirvana is solely recognized as being distinct. Buddhists can speak in conventional terms of the soul or of self as a matter of convenience, but only under the conviction that ultimately "we" are changing entities. At death, the body and mind disintegrate; if the disintegrating mind contains any remaining traces of karma, it will cause the continuity of the consciousness to bounce back an arising mind to an awaiting being, that is, a fetus developing the ability to harbor consciousness. Thus, in Buddhist teaching, a being that is born is neither entirely different nor exactly the same as it was prior to rebirth.

However, scholars such as Shiro Matsumoto have argued that a curious development occurred in Mahayana Buddhist philosophy, stemming from the Cittamatra and Vijnanavada schools in India: although this school of thought denies the permanent personal selfhood, it affirms concepts such as Buddha-nature, Tathagatagarbha, Rigpa, or "original nature". Matsumoto argues that these concepts constitute a non- or trans-personal self, and almost equate in meaning to the Hindu concept of Atman, although they differ in that Buddha-nature does not incarnate. One should note the polarity in Tibetan Buddhism between shes-pa (the principle of consciousness) and rig-pa (pure consciousness equal to Buddha-nature). The concept of a person as a tulku provides even more controversy. A tulku has, due to heroic austerities and esoteric training, achieved the goal of transferring personal identity from one rebirth to the next (for instance, Tibetans consider the Dalai Lama a tulku). The mechanics behind this work as follows: although Buddha-nature does not incarnate, the individual self comprises skandhas or components that undergo rebirth. For an ordinary person, skandhas cohere in a way that dissolves upon the person's death. So elements of the transformed personality re-incarnate, but they lose the unity that constitutes personal selfhood for a specific person. In the case of tulkus, however, they supposedly achieve a "crystallization" of skandhas in such a manner that the skandhas do not "disentangle" upon the tulku's death; rather, a voluntary reincarnation occurs. In this new birth, the tulku possesses a continuity of personal identity rooted in the fact that the consciousness or shes-pa (which equates to a type of skandha called vijnana) has not dissolved after death, but has sufficient durability to survive in repeated births. The compatiblility of these concepts with Buddhist orthodoxy remains in dispute.

Many modern Buddhists, particularly in Western countries, reject the concept of rebirth or reincarnation as incompatible with the concept of anatta. They take the view that if there is no abiding self and no soul then nothing remains to be reborn. Stephen Batchelor, notably, discusses this issue in his book Buddhism Without Beliefs. However, the question arises: if a self does not exist, who thinks/lives now? Buddhists hold the view that thought itself thinks: if you remove the thought, there's no thinker (self) to be found. A detailed introduction to this and to other basic buddhist teachings appears in What the Buddha taught by the Buddhist monk Walpola Rahula. Gurdjieff taught that man has no soul. Rather, man must create a soul while incarnate whose substance could withstand the shock of death. Without a soul, Gurdjieff taught, man will "die like a dog."

Christian beliefs: - Various opinions

Most Christians regard the soul as the immortal essence of a human, and that after death, God either rewards or punishes the soul. Different Christian groups dispute whether this reward/punishment depends upon doing good deeds, or merely upon believing in God and in Jesus.

Many Christian scholars hold, as Aristotle did, that "to attain any assured knowledge of the soul is one of the most difficult things in the world". Augustine, one of the most influential early Christian thinkers, described the soul as "a special substance, endowed with reason, adapted to rule the body". Philosopher Anthony Quinton said the soul is a "series of mental states connected by continuity of character and memory, [and] is the essential constituent of personality. The soul, therefore, is not only logically distinct from any particular human body with which it is associated; it is also what a person is". Richard Swinburne, a Christian philosopher of religion at Oxford University, wrote that "it is a frequent criticism of substance dualism that dualists cannot say what souls are.... Souls are immaterial subjects of mental properties. They have sensations and thoughts, desires and beliefs and perform intentional actions. Souls are essential parts of human beings..."

The origin of the soul has provided a sometimes vexing question in Christianity; the major theories put forward include creationism, traducianism and pre-existence.

Other Christian beliefs differ:

1. A few Christian groups do not believe in the soul, and hold that people cease to exist, both mind and body, at death; they claim however that God will recreate the minds and bodies of believers in Jesus at some future time, the "end of the world."
2. Another minority of Christians believe in the soul, but don't regard it as inherently immortal. This minority also believes the life of Christ brings immortality, but only to believers.
3. Medieval Christian thinkers often assigned to the soul attributes such as thought and imagination as well as faith and love: this suggests that the boundaries between "soul" and "mind" can vary in different interpretations.
4. Jehovah's Witnesses hold beliefs that equate the soul with the person rather than with a spirit or a force which leaves the body at or after death. (Gen.2:7; Ezek.18:4, KJV)
5. The soul sleep theory states that the soul goes to "sleep" at the time of death, and stays in this quiescent state until the last judgment.
6. The "absent from the body, present with the Lord" theory states that the soul at the point of death, immediately becomes present at the end of time, without experiencing any time passing between.
7. The "purgatory" theory states the soul, if imperfect, spends a period of time purging or cleansing before becoming ready for the end of time.
8. The present Catechism of the Catholic Church defines the soul as "the innermost aspect of man, that which is of greatest value in him, that by which he is most especially in God's image: 'soul' signifies the spiritual principle in man."
9. Swedenborgianism teaches that each person's soul is created by the Lord at the same time as the physical body is developed, that the soul is the person himself or herself, and that the soul is eternal and has an eternal spiritual body that is substantial without being material. After the death of the body, the person become immediately conscious in the spiritual world.

In favor of a conscious non-material entity ("soul") that survives bodily death

Some traditional Christians argue that the Bible teaches the survival of a conscious self after death. They interpret this as an intermediate state, before the deceased unite with their Resurrection bodies and restore the psychosomatic unity that existed from conception and which death disrupts. These Christians point out:

• Rachel's death in Genesis 35:18 equates with her soul (Hebrew nephesh) departing. And when Elijah prays in 1 Kings 17:21 for the return of a widow's boy to life, he entreats, "O LORD my God, I pray you, let this child's nephesh come into him again". So death meant that something called nephesh (or "soul") became separated from the body, and life could return when this soul returned.


• Jesus told the repentant thief on the cross, "I say to you, today you will be with me in paradise" (Luke 23:43). Interpretation: that very day, the thief will in a conscious way have fellowship with Christ in paradise despite the apparent destruction of his body.


• Jesus' account of the rich man and Lazarus, both still conscious at the same time as the rich man's brothers lived on. This scenario preceded Jesus taking the souls of Paradise with Him to heaven, therefore Lazarus remains in Paradise. The rich man stood in another compartment of Sheol where he could see Lazarus but never cross over.


• Matthew 10:28: Jesus says, "And do not fear those who kill the body but cannot kill the soul; rather fear him who can destroy both soul and body in hell." Here, the soul (Greek psyche) appears as something distinct from the body and something which survives the death of the body.


• Phil. 1:21-23, depicting the believer to "depart and to be with Christ", where the aorist infinitive (to depart) links via a single article to a present infinitive (to be with Christ). This linkage shows that the departure and being with Christ occur at the same moment. And since Christ dwells in Heaven, Paul anticipated going to Heaven at death.


• Revelation 6:9-10 portrays the souls (Greek psychas) of martyred saints as conscious and as asking God how long He will refrain from smiting the wicked on Earth. Once more, these saints consciously exist with God in heaven at the same time as evil people exist on the earth.


• Matthew 22 : 23That same day the Sadducees, who say there is no resurrection, came to him (Jesus) with a question. 24“Teacher,” they said, “Moses told us that if a man dies without having children, his brother must marry the widow and have children for him. 25Now there were seven brothers among us. The first one married and died, and since he had no children, he left his wife to his brother. 26The same thing happened to the second and third brother, right on down to the seventh. 27Finally, the woman died. 28Now then, at the resurrection, whose wife will she be of the seven, since all of them were married to her?” 29Jesus replied, “You are in error because you do not know the Scriptures or the power of God. 30At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven. 31But about the resurrection of the dead – have you not read what God said to you, 32‘I am the God of Abraham, the God of Isaac, and the God of Jacob’[Exodus 3:6]? He is not the God of the dead but of the living.” 33When the crowds heard this, they were astonished at his teaching.


• 1 Corinthians 15 : 12But if it is preached that Christ has been raised from the dead, how can some of you say that there is no resurrection of the dead? 13If there is no resurrection of the dead, then not even Christ has been raised. 14And if Christ has not been raised, our preaching is useless and so is your faith. 15More than that, we are then found to be false witnesses about God, for we have testified about God that he raised Christ from the dead. But he did not raise him if in fact the dead are not raised. 16For if the dead are not raised, then Christ has not been raised either. 17And if Christ has not been raised, your faith is futile; you are still in your sins. 18Then those also who have fallen asleep in Christ are lost. 19If only for this life we have hope in Christ, we are to be pitied more than all men. (...) 29Now if there is no resurrection, what will those do who are baptized for the dead? If the dead are not raised at all, why are people baptized for them? 30And as for us, why do we endanger ourselves every hour? 31I die every day–I mean that, brothers–just as surely as I glory over you in Christ Jesus our Lord. 32If I fought wild beasts in Ephesus for merely human reasons, what have I gained? If the dead are not raised, “Let us eat and drink, for tomorrow we die.”[Isaiah 22:13] (...) 35But someone may ask, “How are the dead raised? With what kind of body will they come?” 36How foolish! What you sow does not come to life unless it dies. 37When you sow, you do not plant the body that will be, but just a seed, perhaps of wheat or of something else. 38But God gives it a body as he has determined, and to each kind of seed he gives its own body. 39All flesh is not the same: Men have one kind of flesh, animals have another, birds another and fish another. 40There are also heavenly bodies and there are earthly bodies; but the splendor of the heavenly bodies is one kind, and the splendor of the earthly bodies is another. 41The sun has one kind of splendor, the moon another and the stars another; and star differs from star in splendor. 42So will it be with the resurrection of the dead. The body that is sown is perishable, it is raised imperishable; 43it is sown in dishonor, it is raised in glory; it is sown in weakness, it is raised in power; 44it is sown a natural body, it is raised a spiritual body. If there is a natural body, there is also a spiritual body. 45(...) 46The spiritual did not come first, but the natural, and after that the spiritual. 47The first man was of the dust of the earth, the second man from heaven. 48As was the earthly man, so are those who are of the earth; and as is the man from heaven, so also are those who are of heaven. 49And just as we have borne the likeness of the earthly man, so shall we bear the likeness of the man from heaven.

Christian Gnosticism: Valentinus

In early years of Christianity, the Gnostic Christian Valentinus of Valentinius (circa 100 - circa 153) proposed a version of spiritual psychology that accorded with numerous other "perennial wisdom" doctrines. He conceived the human being as a triple entity, consisting of body (soma, hyle), soul (psyche) and spirit (pneuma). This equates exactly to the division one finds in St. Paul’s Epistle to Thessalonians I, but enriched: Valentinus considered that all humans possess semi-dormant "spiritual seed" (sperme pneumatike) which, in spiritually developed Christians, can unite with spirit, equated with Angel Christ. Evidently his spiritual seed corresponds precisely to shes-pa in Tibetan Buddhism, jiva in Vedanta, ruh in Hermetic Sufism or soul-spark in other traditions, and Angel Christ to Higher Self in modern transpersonal psychologies, Atman in Vedanta or Buddha nature in Mahayana Buddhism. In Valentinus’ opinion, spiritual seed, the ray from Angel Christ, returns to its source. This is true resurrection (as Valentinus himself wrote in The Gospel of Truth: "People who say they will first die and then arise are mistaken. If they do not receive resurrection while they are alive, once they have died they will receive nothing."). In Valentinus’ vision of life human bodies go to dust, soul-sparks or spiritual seeds unite (in realised Gnostics) with their Higher Selves/Angel Christ and the soul proper, carrier of psychological functions and personalities (emotions, memory, rational faculties, imagination,...) will survive - but will not go to Pleroma or Fullness (the source of all where resurrected seeds that have realised their beings as Angels Christ return to). The souls stay in "the places that are in the middle", the worlds of Psyche. In time, after numerous purifications, the souls receive "spiritual flesh", i.e. a resurrection body. This division appears rather puzzling, but not dissimilar to Kabbalah, where neshamah goes to the source and ruach is, undestructed and indestructible, but unredeemed, relegated to a lower world. Similarly, according to Valentinus, complete resurrection occurs only after the end of Time (in the Christian worldview), when transfigured souls who have acquired spiritual flesh finally re-unite with the perfect, individual Angel Christ, residing in the Pleroma. Valentinus sees this as final salvation.

Many non-denominational Christians, and indeed many people who ostensibly subscribe to denominations having clear-cut dogma on the concept of soul, take an "à la carte" approach to the belief, that is, they judge each issue on what they see as its merits and juxtapose different beliefs from different branches of Christianity, from other religions, and from their understanding of science.

Hindu beliefs

In Hinduism, the Sanskrit word most closely corresponding to soul is "Atman", which can mean soul or even God. It is seen as the portion of Brahman within us. Hinduism contains many variant beliefs on the origin, purpose, and fate of the soul. For example, advaita or non-dualistic conception of the soul accords it union with Brahman, the absolute uncreated (roughly, the Godhead), in eventuality or in pre-existing fact. Dvaita or dualistic concepts reject this, instead identifying the soul as a different and incompatible substance.

Jainist beliefs

Jainists believe in a jiva, an immortal essence of a living being analogous to a soul, subject to the illusion of maya and evolving through many incarnations from mineral to vegetable to animal, its accumulated karma determining the form of its next birth.

Jewish beliefs

Jewish views of the soul begin with the book of Genesis, in which verse 2:7 states, "the LORD God formed man from the dust of the earth. He blew into his nostrils the breath of life, and man became a living being." (New JPS)

The Hebrew Bible offers no systematic definition of a soul; various descriptions of the soul exist in classical rabbinic literature.

Saadia Gaon, in his Emunoth ve-Deoth 6:3, explained classical rabbinic teaching about the soul through the lens of neo-Aristotelian philosophy. He held that the soul comprises that part of a person's mind which constitutes physical desire, emotion, and thought.

Maimonides, in his The Guide to the Perplexed, explained classical rabbinic teaching about the soul through the lens of neo-Aristotelian philosophy, and viewed the soul as a person's developed intellect, which has no substance.

Kabbalah (esoteric Jewish mysticism) saw the soul as having three elements. The Zohar, a classic work of Jewish mysticism, posits that the human soul has three elements, the nefesh, ru'ah, and neshamah. A common way of explaining these three parts follows:

Nefesh - the lower or animal part of the soul. It links to instincts and bodily cravings. It is found in all humans, and enters the physical body at birth. It is the source of one's physical and psychological nature.
The next two parts of the soul are not implanted at birth, but are slowly created over time; their development depends on the actions and beliefs of the individual. They are said to only fully exist in people awakened spiritually:

Ruach - the middle soul, or spirit. It contains the moral virtues and the ability to distinguish between good and evil. In modern parlance, it equates to psyche or ego-personality.
Neshamah - the higher soul, Higher Self or super-soul. This distinguishes man from all other life forms. It relates to the intellect, and allows man to enjoy and benefit from the afterlife. This part of the soul is provided both to Jew and non-Jew alike at birth. It allows one to have some awareness of the existence and presence of God. In the Zohar, after death Nefesh disintegrates, Ruach is sent to a sort of intermediate zone where it is submitted to purification and enters in "temporary paradise", while Neshamah returns to the source, the world of Platonic ideas, where it enjoys "the kiss of the beloved". Supposedly after resurrection, Ruach and Neshamah, soul and spirit re-unite in a permanently transmuted state of being.
The Raaya Meheimna, a Kabbalistic tractate always published with the Zohar, posits two more parts of the human soul, the chayyah and yehidah. Gershom Scholem wrote that these "were considered to represent the sublimest levels of intuitive cognition, and to be within the grasp of only a few chosen individuals":

Chayyah - The part of the soul that allows one to have an awareness of the divine life force itself.

Yehidah - the highest plane of the soul, in which one can achieve as full a union with God as is possible.

Extra soul states

Both Rabbinic and kabbalistic works also posit a few additional, non-permanent states to the soul that people can develop on certain occasions. These extra souls, or extra states of the soul, play no part in any afterlife scheme, but are mentioned for completeness.

Ruach HaKodesh - a state of the soul that makes prophecy possible. Since the age of classical prophecy passed, no one receives the soul of prophecy any longer.
Neshamah Yeseira - The supplemental soul that a Jew experiences on Shabbat. It makes possible an enhanced spiritual enjoyment of the day. This exists only while one observes Shabbat; it can be lost and gained depending on one's observance.
Neshamah Kedosha - Provided to Jews at the age of majority (13 for boys, 12 for girls), and related to the study and fulfillment of the Torah commandments. It exists only when one studies and follows Torah; it can be lost and gained depending on one's study and observance.
For more detail on Jewish beliefs about the soul see Jewish eschatology.

Other religious beliefs and views

In Egyptian Mythology, a individual was believed to be made up of various elements, some physical and some spiritual. See the article Egyptian soul for more details.

These are the two parts which the ancient Chinese believed constitute every person's soul. The p‘o is the visible personality indissolubly attached to the body, while the hun is its more ethereal complement also interpenetrating the body, but not of necessity always tied to it. The hun in its wanderings may be either visible or invisible; if the former, it appears in the guise of its original body, which actually may be far away lying in a trance-like state tenanted by the p‘o. And not only is the body duplicated under these conditions, but also the garments that clothe it. Should the hun stay away permanently, death results.

Some transhumanists believe that it will become possible to perform mind transfer, either from one human body to another, or from a human body to a computer. Operations of this type (along with teleportation), raise philosophical questions related to the concept of the Soul.

Crisscrossing specific religions, the phenomenon of therianthropy and belief in the existence of otherkin also occur. One can perhaps better describe these as phenomena rather than as beliefs, since people of varying religion, ethnicity, or nationality may believe in them. Therianthropy involves the belief that a person or his soul has a spiritual, emotional, or mental connection with an animal. Such a belief may manifest itself in many forms, and many explanations for it often draw on a person's religious beliefs. Otherkin hold similar beliefs: they generally see their souls are entirely non-human, and usually not of this world.

Another fairly large segment of the population, not necessarily favoring organized religion, simply label themselves as "spiritual" and hold that both humans and all other living creatures have souls. Some further believe the entire universe has a cosmic soul as a spirit or unified consciousness. Such a conception of the soul may link with the idea of an existence before and after the present one, and one could consider such a soul as the spark, or the self, the "I" in existence that feels and lives life.

Some believe souls in some way "echo" to the edges of this universe, or even to multiple universes with compiled multiple possibilities, each presented with a slightly different energy version of itself. The science fiction author Robert Heinlein, for example, has explored such ideas.

In Surat Shabda Yoga, the soul is considered to be an exact replica and spark of the Divine. The purpose of Surat Shabd Yoga is to realize one’s True Self as soul (Self-Realization), True Essence (Spirit-Realization) and True Divinity (God-Realization) while living in the physical body.

Science and the soul

Western science and medicine do recognize the concept of soul or the idea of a soul entity, but mainly as an element of Folk psychology. In contrast, Traditional Chinese medicine accepts the existence of a soul as more than just an idea (see Shen). The two dominant scientific approaches to study of the soul can be distinguished by the emphasis they place on two alternative hypotheses:

Hypothesis 1. Materialistic accounts of human brain function and scientific study of cultural belief systems will ultimately tell us everything we need to know about the common human belief in a non-material soul.

Hypothesis 2. Non-material conscious entities exist, but conventional materialistic science does not have the tools needed to study the non-material soul. Only by taking seriously the idea of non-material entities will science develop the means to objectively study the soul.

Working within the Scientific method, it is a common practice to have several alternative hypotheses. Testing multiple hypotheses is healthy for science because it challenges everyone to keep an open mind and not become overly confident that we know all the answers. Openly discussing both types of hypotheses about the soul (see above) is important for science because many non-scientists feel that Western materialistic science has not given fair attention to the possibility of a non-material soul.

Scientific study of the soul has been hampered by both technical and sociological constraints. A serious technical limitation for materialistic approaches to the soul is that the details of brain function are still being discovered. No detailed account yet exists of how complex human beliefs arise through brain activity that is shaped by a complex human social environment. Many scientists are involved in foundation building that will eventually lead to a detailed materialistic account of the soul while few risk even mentioning the word “soul” in their professional work.

A search of the PubMed research literature database shows the following numbers of articles with the indicated term in the title:

brain – 167,244
consciousness – 2,918 (842, 29%, of these articles also include “brain” in the database entry)
soul - 552 (40, 7%, of these articles also include “brain” in the database entry. Many of these articles deal with medical ethics issue such as the implications of religious beliefs on decisions about life support for people in persistent vegetative states)
There are over 6,000 articles in the PubMed database dealing with both consciousness and the soul. These aarticles represent the output of a newly forming scientific sub discipline attempting to account for consciousness in terms of brain function. There are only 100 entries in the PubMed database that mention both the brain and the soul. So far, there has been no way found to objectively link material brain processes to a non-material soul.

A serious constraint on the scientific study of non-material entities is that past attempts to scientifically study many phenomena that seem to involve non-material processes or entities (for example, paranormal phenomena) have not shown a record of scientific progress and have been dominated by pseudoscientific approaches. Working scientists naturally gravitate towards topics of study that offer the likelihood of rapid progress and minimize controversies that taint scientific reputations.

Materialistic Science and the Soul

Popular presentation of the dominant scientific view of the soul often uses the "computer paradigm", which compares the brain to hardware and the mind (mental processes traditionally subsumed under the concept of "soul") to software. The departure of a brain/hardware leaves no place for functioning mind/software. This eliminative approach to the soul is exemplified by Paul Churchland and his book The Engine of Reason, The Seat of the Soul. In that book, Churchland argues that there is no need for the idea of a non-material soul, that we can fully account for the soul in terms of material brain activity, and that the link between the brain and consciousness is primarily a matter of information processing that can be understood in terms of computational models.

Some, like the famous French neurologist Jean Pierre Changeaux, deny the appropriateness of the computer paradigm and propose an analogy with the anharmonic oscillator from physics. Needless to say, both notions have dismissed the concept of soul as a self-sustaining entity.

Some investigators have tried to measure the soul, for example by attempting to measure the weight of a person just before and just after death in hopes of determining the weight of a soul. The results of these experiments remained equivocal, especially due to conflicting reports on the findings, and do not rank as good science.

Francis Crick's book The Astonishing Hypothesis has the subtitle, "The scientific search for the soul". Crick holds the position that one can learn everything knowable about the human soul by studying the workings of the human brain.

In his book Consilience, E. O. Wilson took note of the fact that sociology has identified belief in a soul as one of the universal human cultural elements. Wilson suggested that biologists need to seriously investigate how human genes predispose people to believe in a soul.

Daniel Dennett has championed the idea that the human survival strategy depends heavily on adoption of the intentional stance, a behavioral strategy that predicts the actions of others based on the expectation that they have a mind like one's own (see theory of mind). Mirror neurons in brain regions such as Broca's area may facilitate this behavioral strategy. The intentional stance, Dennett suggests, has proven so successful that people tend to apply it to all aspects of human experience, thus leading to animism and to other conceptualizations of soul.

Scientific approaches for study of a non-material soul

A frequently documented phenomenon involves very young children (under the age of five) saying seemingly random phrases, spontaneously, with no readily traceable originating source, for example: "I remember when I died before". The parent-controlled flow of information that reaches the child does not account for the phrase, which most hearers ignore. Some people believe that a child can express past-life memories in this way.

Dr. Ian Stevenson, a prominent member of the scientific community, has spent over 40 years devoted to the study of children who have spoken about concepts seemingly unknown to them. Dr Stevenson maintains a thorough scientific method of interview and observation. In each case, Dr. Stevenson methodically documents the child's statements. Then he identifies the deceased person the child allegedly identifies with, and verifies the facts of the deceased person's life that match the child's memory. He even matches birthmarks and birth defects to wounds and scars on the deceased, verified by medical records. His strict methods systematically rule out all possible "normal" explanations for the child’s memories. However, it should be noted that a significant majority of Dr. Stevenson's reported cases of reincarnation originate in Eastern societies, where dominant religions often permit the concept of reincarnation. Dr. Ian Stevenson results could also be discredited as a form of cold reading where the child can make any claims, and with all the cases of deaths in human history to search through the chances of finding a match to those claims are very likely.